A method for crosslinking a fluorinated elastomer is known to influence the properties of the resulting crosslinked product. In particular, a perfluoroelastomer is known to be not easy to crosslink. Therefore, various crosslinking methods have been proposed to improve the properties of crosslinked products or to improve crosslinking reactivities.
For example, the following methods have been proposed as methods for crosslinking a perfluoroelastomer.
(1) a crosslinking method wherein a perfluoroelastomer having nitrile groups as crosslinking sites, is reacted in the presence of an organic tin compound, to form a triazine ring from three nitrile groups (Patent Document 1).
(2) a crosslinking method wherein a perfluoroelastomer having a bromine atom as a crosslinking site, is reacted with triallyl isocyanurate (hereinafter referred to also as TAIC) as a crosslinking aid, in the presence of a peroxide (Patent Document 2).
(3) a crosslinking method wherein a perfluoroelastomer having an iodine atom as a crosslinking site at a polymer chain terminal, is reacted with TAIC in the presence of a peroxide (Patent Documents 3 and 4).
(4) a crosslinking method wherein a perfluoroelastomer having an iodine atom at a polymer chain terminal, is reacted with 1,6-divinyl perfluorohexane as a crosslinking aid in the presence of a peroxide (Patent Document 5).
However, the crosslinked product obtained by the method of (1) is not sufficient in chemical resistance, particularly in amine resistance.
The crosslinked product obtained by the method of (2) or (3) has a crosslinking point of an isocyanurate ring and thus is not sufficiently heat resistant.
The crosslinked product obtained by the method of (4) is excellent in heat resistance, but is not sufficient in chemical resistance, particularly in amine resistance.
Therefore, development of a perfluoroelastomer composition which is excellent in crosslinking reactivity and of which a crosslinked product is excellent in chemical resistance and heat resistance, is desired.